This invention relates to a rotary compressor or rotary displacement pump (hereafter collectively also referred to as a rotary fluid displacement machine) including a stator which defines work chambers and further has a bearing for a drive shaft; a rotor mounted on the drive shaft and operating according to the rotary vane principle. The rotor divides the work chamber into at least two compartments. The invention further relates to a gas refrigerating machine which includes such compressor or pump and which operates according to the Stirling or Vuilleumier principle.
Rotary fluid displacement machines of the above-outlined type operate preponderantly according to the rotary vane principle. The fluid inlet and the outlet are provided in the stator in a stationary manner such that a substantially constant vacuum and, respectively, pressure prevails at the inlet and outlet. The use of these structures for gas refrigerating machines is therefore only conditionally possible.
Thus, regenerative gas refrigerating machines which operate according to the Stirling or the Giffort-McMahon principle preponderantly use piston pumps.
The use of such regenerative gas refrigerating machines is at the present time limited to the cryogenic temperature range (below -100.degree. C.) because in the higher temperature range (between 100.degree. C. and 0.degree. C.) the competitiveness of these machines compared to the conventionally widely used cold vapor principle is questionable. As a reason the relatively high technological input of regenerative gas refrigerating machines is cited.
A diagrammatic illustration of a conventional gas refrigerating machine operating according to the Stirling principle is shown in FIGS. 1 and 2.
The conventional gas refrigerating machine includes a compressor 1, a displacement pump 2, a heat releasing heat exchanger 3, a regenerator 4 and a heat absorbing heat exchanger 5. The displacement piston 2 separates the cylinder 6 into a cold chamber 7 and a warm chamber 8. As shown in FIG. 1, the components are coupled to one another by means of a gas conduit which, similarly to the work chambers, is filled with a gaseous medium, also referred to as the working gas. To obtain the cyclic refrigeration process, the piston of the compressor 1 and the piston of the displacement pump 2 have to move in a coordinated manner. For this purpose, because of technological boundary conditions, as a rule harmonic motions are chosen in which the phase shift in the motions of the two pistons is one-fourth of a cycle as shown in FIG. 2 which illustrates the volume variation of the compression chamber (curve 9), the cold chamber (curve 11) and the warm chamber (curve 10) as a function of time.
The mechanical drive of the compressor and pump pistons is effected in conventional structures by a relatively complex cranking mechanism and a common drive shaft.